Pneumatic spring



J. W. KUHN PNEUMATIC SPRING March 5, 1940.

6 Sheets-Sheet l Filed Dec. 12, 1936 March 5, 1940. l J, W KUHN 2,192,355

/ 23 INVENTOR.

:john WKwhn BY @Omi JWM,

ATTORNEYS March 5, 1940. J. w. KUHN PNEUMATIC SPRING Filed Dec. 12, 1956 6 Sheets-Sheet 5 l I I l INVENTOR f0/m W ,Kahn

ATTORNEYS I /flllllllllllnlnlll March 5, 1940. J, w KUHN 2,192,355

PNEUMATIC SPRING lFiled Dec. 12, 1956 6 Sheets-Sheet 4 1N VENTOR.

BY @M Lm ATTORNEYS J. W. KUHN PNEUMATIC SPRING March 5, 1940.

Filed Dec. l2, 1956 6 Sheets-Sheet 5 INVENTOR. I fo/m WlIZl/hn MT M,

ATTORNEYS March 5, 1940. J, w KUHN 2,192,355

PNEUMATIC SPRING Filed Deo. 12, 193e e sheets-sheet s Y 4f 4e ,f 44 .47

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ATTORNEYS Banned Mir. s, 1940 Y l y 2,192,355

. UNITED l STATES 'PATENT OFFICEk PNEUMATIC SPRING John K uhn, Akron, Ohio, assigner to The Firestone 'Ifire & Rubber Company, Akron, ohio,

a corporation of Ohio v Application December 12, 1936, Serial No. 115,616 9 Claims. (Cl. 267-35) This invention relates to improvements on the but on the contrary are adaptable to the spiral. constructions shown in Patent No. 2,056,106 and bead constructions. In fthe spiral bead designs, is a continuation in part of my pending applithe cord reinforcing members are identical with cation Ser. No. 91,186, filed July 1'7, 1936. The that of the annular bead designs, with one ex- 5 invention relates to improvements on air-,springs ception, namely, they are not endless. In the 5 and particularly to bead reinforcements and has spiral bead designs, the cord reinforcing memfor its primary object to provide a practical conbers are wound spirally around the spiral construction of compressed air-spring which may be cave, beaded portion of the fabric o-f the casing, utilized iny various capacities and u nder various and exteriorly of sar'ne, with the ends of the re- A conditions, such Aas the suspension of automoinforcing members merging in to and embedded 1U biles, railway. cars, farm machinery, and to be ,l in annular beads. To further reinforce the used in conjunction with certain types of stabeads, strips of cord fabric are utilized in which tionary machinery. the individual cords extend lengthwise. These One of the primary objectsof the invention strips of fabric are Wound around the concave consists in the provision of a conventional metal .grooves 'formed by the beaded portions of the l5 coil spring sealed in a practical manner within fabric of the casing, in the grooves formed therethe interior of a pneumatic spring proper, to be by andexteriorly thereof. In the annular bead utilized as an auxiliary and emergency spring type this auxiliary reinforcing cord fabric is under certain conditions. wound in one or more layers, and in the annular' A further object of the invention resides in groove formed by the annular beaded portions of 20 the provision of automatic self-snubbing springs the fabric of the casing, and in the spiral bead which are designed to possess high shock absorbtype, this auxiliary reinforcing cord fabric is ing qualities and to be controlled by manual or wound spirally in one or more layers. remote control to meet varying load requi're- Another object of the inventiomresides in the mentsprovision of a conventional metal coil spring or 25 Another object of the invention consists in progroup of springs, embedded in the spiral beaded viding cord reinforcing mem-bers for springs havportion of the fabric of the casing, and merging ing along expansion stroke anda high frequency. into annular base ends in the spiral bead type These cord reinforcements are positioned in the and in the portion of a spring having a spiral beaded portions of the springs and are designed bead. In this manner this conventional metal 30 to resist internal air-pressure and retainV the spring or multiple spring serves as a reinforcing spring proper' in its molded shape when inflated member, resists internal air-pressure exerted on with air. the fabric of the casing, and acts as an auxiliary Another object of the invention resides in `prospring. y

viding the initial reinforcing members, which One of the major advantages of the cord rein- 35 are made up of a ply or plies of cord fabric, prefforcing members, as compared with Wire reinforcerably an even number of plies, and cut so that ing members, resides in the lfact that rubberized the individual cords of each ply make acute or rubber insulated cord reinforcing fabric will angles with the horizontal, the ends. of each inform a better union with the rubberized fabric of 40 dividual cord terminating, preferably high on the casing than will the wire.

the side-walls of the adjacent ribs. Other objects and advantages of the invention Another object of the invention consists in the v will be apparent from the following description provision of annular, endless reinforcing ropewhen taken in connection with the accompanying like bands, in which the individual cords of the drawings, in which,

"f reinforcing members pass spirally around them- Figure 1 is anelevational view partly in section 45 selves. These endless rope-like reinforcing of one form of spring. members are produced by employing one or more Figure 2 is a vertical sectional view through plies of cord reinforcing material formed in an another form of spring and in which a convenendless band, and identical to that of the initial tional metal coil spring is mounted axially therereinforcing members, these bands are then rolled` in. l

upon vthemselves from an outer edge, forming a Figure 3 'is a spring casing similar to that of rope-like structure. Figure 2, built up on a steel mandrel in semi-flat `llnother object of the invention consists in the form, and partly in section.

provision ofl cord reinforcing members whicnare Figure 4 is a completed elevational view of the lnot limited to the annular bead construction; casing of Figure 3, and partly in section.

Figure 5 is an elevational view, partly in section, of a spiral bead spring casing built up on a mandrel in semi-flat form.

Figure 6 is an elevational View partly in section of the, construction shown in Figure 5.

Figure 7 is a plan view of-one of the cord reinforcing members, before being assembled into an endless band, showing two pliesof cord fabric assembled together, and the acute angles of the individual cords in each ply, also showing how the individual cords of one ply cross those of the other ply and in an opposite direction.

Figure 8 is an elevational view, partly in section, of an endless band embodying the features of Figure 7 and showing a thin film of uncured adhesive rubber which holds the cords of each ply together in fabric form, and showing a cross section of some of the cords much larger than actual size in conventional cord fabric although the size o f the individual cords may be varied as desired.

Figure 9 is an elevational view of the endless band of Figure 8 with the thin filmcoating of adhesive rubber removed, vand some of the cords broken away to show the acute angles of the individual cords in the assembled endless band before being positioned in the spring proper.

Figure 10 is an elevational view, showing the cylindric form of Figure 8 partly rolled into ropelike form.

Figure 11 is a view, partly broken away, of the reinforcing member completely rolled in an endless rope-like form to provide an endless rope- -like reinforcing member to be utilized in conjunction with the reinforcing member of Figure 8.

Figure 12 is a plan view of one of the cord reinforcing members taken on l@ scale of Figures 5 and y6 showing two plies of cord fabric assembled together with some of the cords of the outer ply broken awayto more clearly show the acute angles of the individual cords in both plies. This reinforcing member is identical with that of Figure 7 with one exception, it is much longer, and is not made endless like Figure '7 but is to be wound spirally in the spiral bead Figure 15 is a plan view of the construction ofv Figure 14 showing the housing supports and connections'to accommodate the pneumatic springs, and in which provision has been made for conventionalmetal springs to be utilized as auxiliary springs and as a safety factor.

Figure 16 is an enlarged fragmentary view of the lower portion of the construction shown in Figure 1 in which is more clearly shown the initial and secondary reinforcing members, and also the transverse reinforcing fabric.

Referring to the drawings in greater detail and especially to Figures 1 and 16, the numeral I indicates a metal casing which envelops the upper end of the spring member indicated gene'rally by the numeral 2. The vertical length of the casing I may be varied as desired, but in Figure' -1 shown as extending over about onenaif the length of the spring. The member v2` is of generally cylindrical form and is built up oftire material including conventional box-weave or cord fabric plies in the casing proper, India rubber, insulated cord and wire reinforcing material, and sponge rubber.

The pneumatic spring 2 is built up on a man-' drel having the desired configuration and consists of a plurality of annular, spiral, and semiannular beads. In building the spring a layer of rubber indicated by numeral 3, preferably India rubber such as used in conventional inner-tubes for automobile tires, is. employed. This layer of India rubber is placed over and around a mandrel, the outer edges and grooves of the mandrel which correspond to the beaded formations of the casing, having been covered with a suitable cement, and then one or more rubberized and adhesive fabric plys are placed over and around `the layer of rubber 3. 'I'hese rubberized and ad-4 hesive fabric plies are conventional fabrics used in tire construction. The conventional cord, box-weave, and retiform fabrics-may beutilized for this purpose but the cord fabric is preferable.

The number of plies of fabric may of course be varied in accordance with the strength required to resist a given internal air-pressure. The several plies of material are placed over and around themandrel to form beads 4, 5, 6, 'l and 8. Beads 4, 5, 6 and 'I are reinforced with rubberized or rubber insulatedwire 9 and I0. The wire employed is preferably spring wire, and is wound in a spiral form to provide a coil spring construction to function as an auxiliary spring, and to serve as a reinforcing member for the spiral beaded portion of the fabric of .the casing,

thereby resisting internal air-pressure 'exerted on the fabric of the casing proper. y

' Bead 8 which is of annular form, is reinforced with cord fabric in which the normal position of the individual cords of the fabric are lengthwise. The cords are held together with a thin coating of rubber forming a fabric, and it will be noted that the fabric is cut so that the individual cords make acute angles with the horizontal. Each individual cordv passes spirally around' the fabric of the casing, making acute angles with the horizontal, and their ends terminating onv the-.annular ribs II and I2. In each alternate layer' of reinforcing cord fabric the individual cords make acute angles with the horizontal in an opposite direction, thereby serving to retain the shape of the bead. The position of one of the individual cords is indicated by letters A, B and C starting at letter A. The cord winds around the fabric of the casing from A to B, and then terminates at C. Of course this-position would vary in proportion to any variation inthe acute angles of the individual cords. As a further reinforcement of bead 8, sponge rubber I3 is inserted as, a support for transverse reinforcing fabric I 4, and to 'still further reinforce bead 8 a long strip of cord fabric in which the individual cords are lengthwise, is wrapped around and in the concave groove formed by the beaded portion of the fabric of the casing indicated as b ead 8 but external of the fabric of the casing the same as the initial reinforcing member. 'I'hree layers of this reinforcing fabric are disclosed in this construction and are indicated by numeral I5. This construction in connection with bead 8 provides for greater resist- Vance to internal air-pressure, greater flexibility and Agreater compressibility of this part of the wires are a part of bead and provide a spiral spring-like reinforcing member for the adjacent fabric of the casing. Bead 6 is similar to bead 5, but is ofl smaller diameter so as to permit the convolutions of bead 5 to overlap the convolutions of lbead 6, thereby providing greater com` pressibility. The spiral windings of bead 6 also start at the point X and terminate at the point X-A. The beads 1 are formed by a series of rubber insulated spring wires wound in right and left-hand spiral form. The left-hand wires start from the point X-A and merge into annular bead 4-B at point X-D, and the right-hand' group of wires start from point X-B and merge into the bead 4-B at point X-C. Another group or series of right and left-hand rubber insulated wires start and terminate at the same points as beads 1 and are identical, providing the diamond shape bead formations and consequent diamond shape ribs. These beads are indicated in part by dotted lines. The right and left-hand arrangement of these groups of spiral wires provides opposing forces which counteract each other when the spring is operated; thereby preventing lateral twist in this part `of the casing, in addition to providing auxiliary springlike action due to the spring wire utilized and the spiral bead formations, and reinforcing members which resist the internal air-pressure exerted on the fabric of the casing in this part of the spring. Reinforcing spring wires I0 may be replaced by soft wires or cord fabric and still retain the spring-like action of the heavy reinforcing wire 9.

The spaces between the ribs formed by beads 5, 6 and 'l are filled with highly compressible SPOnge rubber I6 which facilitates resilient action and compressibility of the' spring in addition to forming a base for an outer rubber cover l1. The entire spring is covered with this outer layer of India rubber which protects the fabrics from moisture, abrasion, and premature decay. The outer surface of this layer of rubber I1 is provided with diamond shaped molded depressions in its exterior surface to enhance resilient action and compressibility.

The ends of the casing constitute sheets of India rubber which are continuations of the initial layer of India rubber 3, and are sealed airtight, forming an air-tight'casing. For the purpose of iniating the spring, a conventional airvalve such as used in automobile tires is inserted and sealed in `,the lower continuation of the initial layer yof India rubber 3. indicated by numeral I8. l Y.

The spring casing described above is formed into upperand lower chambers by means of a partition |9. In this partition a ball check-valve 20 is provided to retard the flow of air from one chamber lto the other; thereby providing a snubbing actionin the spring. To accomplish this action the lower chamber formed with a concave groove in its exterior surface, and the bead 8 of less cross sectional area than the beads of the upper chamber 'thus providing less resistance toweight in the lower' chamber, and greater compressibility (or ratio or compression) to air volume. On compression the air-pressure momentarily becomes greater in the lower cham? ber, thereby lifting valve A2|) permitting the air- This valve is pressure to slowly equalize in the two chambers. On the rebound valve 20 closes by gravity and a lower air-pressure is formed in the lower chamber, the air-pressure then slowly equalizing in the two chambers by leakage around the ball valve 20 thereby snubbing the rebound, and slightly retarding compression.

The entire casing is molded and cured in a.`

manner similar to 'pneumatic tires. and is' then inserted in a housing and base rim support as shown in Fig, 1.

y The -spring of Figure 2 is for heavy duty and is intended for railway car suspension although it is equally adaptable to trucks and buses. Cne of these springs of this design and a cross sectional bead area of 20 inches will support 50,000 pounds at a pound (gauge) air-pressure. It is obvious that a spring of this design is not limited to light loads as in automobile suspension; but can be built to carry a high air-presfsure and consequent heavy loads for a comparainitial layer of rubber 24. This layer of rubber t 24 is similar to the layer of rubber 3 of Figure 1.

4The rubber` formations 23 are seated in cylindrical housings 25 which are formed `in` the'. metal rims 26. The rubber formation 23 at the upper end of the spring `is compressed within `the cylindrical housing 25 with a bolt 49 threaded into the metal base member 22, and'this bolt is liollow and interiorly threaded to receive an ordinary tire valve 48. In order to provide additional safety and to :guard against airleaks an airlock 50 is provided by housing an additional air valve 5| in the upper metal base 22. The lower rubber member 23 is secured in position byv a bolt 52 having its head located in an air seal 53, and it is obvious that air valves may be placed at these points if desired. The pneu- :matic spring proper is allowed to slightly com# pressbefore engaging rthe metal spring 2|, and in this manner metal spring 2| serves as an auxiliary and emergency spring, i. e., as a safety factor in case of a broken air line or a leak in the pneumatic spring. In this manner I provide a construction or design which permits the high shock absorbing qualities of air, and yet retains the safety factor of the conventional metal spring in railway car suspension although this construction is not `limited to railway car suspension,

Numeral 21 indicates a fabric lining on the interior of the spring casing which functions to permit of molding the casing on air, steam or water, and numeral indicates reinforcing cords for the beads ofl the casing.

Figure 3 shows how the annular bead spring design is built up in a fiat manner to facilitate the building of the spring. Or, perhaps we should say, the spring is built up in a dat manner and `then shaped and molded to form as in Figure `1.

in Figure 2 in conjunction with the wire reinforcing members. Reinforcing members 28 of Figures 3 and 4 are also shown in Figures 7, 8 and 9, which show the specific construction. These reinforcing members 28 reinforce the beaded portions of the fabric of the casing indicated by numeral 29, and the beads 29 are furi completed as shown in Figures 10 and 11.

Figures 5 and 6 show how these cord reinforcing members are utilized in conjunction with the spiral bead embodiment of the invention.

Numeral 3| is a reinforcing member which is i more clearly shown in Figure 12, and described above, and is identical with the reinforcing member of Figure 7 with the exception that it is longer and of suiiicient length to wind spirally and exteriorly around the fabric of the casing,

and in the spiral beaded portion thereof, starting at annular bead 32 and merging into annular bead 33. The auxiliary reinforcing member 34 winds spirally around the fabric vof the casing but exteriorly of the initial reinforcing member 3|, starting at annular bead 32 and merging into annular bead 33. This reinforcing member 34 consists of a strip of .cord fabric as shown in Figure 12 rolled and formed in a rope-like reinforcingk member as shown in Figure 13. The two reinforcing members 3| and 34 reinforce the fabric of the casing and are spirally wound Vsprings positioned in redesigned side-frames of the conventional type and indicated by numeral in the spiral beaded portion of thefabric of the casing `indicatedby numeral 35, thereby resisting internal air-pressure exerted on the fabric of the casing.

The casing proper is built up in fiat form as Shown in Figure' 5, and is then sealed at each end with rubber continuations ofithe initial layer of India rubber similar to that of Figure 1 and indicated by numeral 3. the casing are sealed after the casing proper is removed from the mandrel on which it is built. The'caslng proper is then molded and cured in the form as shown in Figure 6.

The initial layer of cord fabric of the reinforcing member shown in Figure 7 is indicated-by numeral 36 and arrows 31; one of the individualA cords is indicated by letters A, B and C of. Figure 7. In the top layer of cord fabric 38 the individual cords extend at a sharpangle to those in the lower layer. The positionof one of the individual cords A, B and C is shown in Figure 1.'

In Figure 8 is shown an endless band formed of the double fabric shown in Figure 7. The cross sectional portionof Figure 8 showsthe' cords on a. large scale, and the thin coating of conventional adhesiveinsulation rubber 39 which holds themdividual cords together and in a fabric form. Letters A, B and C` of Figure 8. show'the position of the individual cord A, B and C of Figure 7.

Numeral 36 of Figure'9 indicates the initial layer of fabric also indicated by numeral 36 vof Figures 7 and 8. Numeral 38 of Figure 9 indicates the top layer of fabric'with some of the cords torn away to show the relative angle`of the cords of the initial layer of fabric 36. Letters A, B and C of Figure 9 show how one of the cords passes spirally'aroundthe annular reinforcing member.

*In Figures 10 and 11 is shown the reinforcing band of Figure 8; modified to produce a rope-like 'I'hat is, the ends of noted that these annular reinforcing bands are made spliceless by the cord formations.

Figures 12 and 13.show spiral bead reinforcing members. In Figure 12 the initial layer of cord fabric is indicated by the numeral 40 and the arrows 4|. This layer of fabric is identical with the initial layer of fabric 36 of Figure 7 indicated by arrows 31, with the exception that it is longer and is of suflicient length to wind spirally around the spiral bead in Figures 5 and 6. The individual cord position indicated by letters D, E and F of Figure 12 is identical with the individual cord position A,` B and C of Figure 7. The top layer of cord fabric 42 of Figure 12 compares with 38 of Figure 7.

in the spiral bead construction will be almost The individual cords designated by letters D, E and F of Figure- 12 when positioned identical in relative position with the cords indicated by letters A, B and C of annular bead construction.

Figure 13 shows how the reinforcing band 0r member of Figure 12 is rolled into a rope-like reinforcing member. The individual cords of this member compare with the individual cords of the annular rope-'like reinforcing member, that is, the cords wind spirally around themselves in a right and left hand spiral form.

Figures 14 and 15 show how the pneumatic springs as described and shown in Figure 2 can -be utilized in conjunction with railway car suspension. Numeral 43 designates the pneumatic manner to conventional metal springs now in common use. On the ends of truck bolster 45 I have provided extension arms 46 which engage the upper ends of conventional metal springs (not Figure 7 in the y shown)A which are to seat in the hollow spaces 41 4of the side frame 44. In this manner the pneumatic spring 43 can be made to carry the load,

and the conventional metal springs which are to be positioned in the hollow spaces 41 will provide safety in case of a-broken air line -and act as auxiliary springs when desired.

The operation of the improved spring construction has been fully described in connection with .the description of the construction, and henceneed not be further referred to.

In accordance with the patent statutes I have described what I now believe tobe the preferred form of construction, but 'inasmuch as various minor changes may be made in the detailspf lconstructidn without departing from the'spirit of the invention it is intended that all such changes'be included within the scope of the appended claims.

What I claim is: v

1. A pneumatic spring device including an iniiatable casing built up of tire material and molded to form a spiral bead and a spring wire of spiral form disposed in said bead.

2. A pneumatic spring device including an inflatable casing Abuilt up ofV tire material and molded to provide right and left handed spiral beads, the convolutions of one 'spiral bead overlapping the convolutions of the other spiral bead, and reinforcing material in said beads.

3. A pneumatic spring device including an inflatable casing built up of tire material and molded to form right and left handed spiral beads and annular beads, and right and left handed spiral reinforcing members disposed in said spiral beads and merging from and into said annular beads.

4. A pneumatic spring device including an inatable casing built up of tire material and molded to form a spiral bead, and highly compressible sponge rubber mounted in the external spaces between said beads.

5. A pneumatic spring device including a casing built up of tire material and molded to form a spiral bead, sponge rubber mounted in the external spaces between the beads, and an outer covering of dense rubber for said casing..

6. A pneumatic spring device including a casing built up of tire material and molded to form a plurality of convolutions and an intermediate annular reinforcing bead, said spring adapted to support a load between the ends thereof, a rubber partition mounted in said casing and secured to the bead to form upper and lower compartments, and an automatic valve mounted in the partition.

7.' A pneumatic spring device includinga casing built up of tire material, said spring adapted yto support a load between the ends thereof, a

valved partition dividing the casing into upper and lower compartments, the lower compartment having ,a greater cross sectional area than the upper compartment.

8. A pneumatic spring device including a casing built up of tire material and provided with a plurality of annular ribs and an,A interposed bead, a layer of rubber having a thickness substantially equal to the thickness of the bead positioned within the bead, and a transverse sheet of reinforcing fabric mounted on the rubber and connected to the inner surface of one of the ribs.

9. A pneumatic spring device including an inilatable casing built up of tire material. and.L provided with a spiral bead and annular beads, said annular and spiral beads being reinforced with inextensible cord reinforcing members, the individual cords of the reinforcing members being covered with a coating of rubber, thereby providing compact beads, and a strong union with the fabric of the casing when molded and cured.

JOHN w. KUHN. 

